1. Field of the Invention
The present invention relates to a motion video decompression system and more particularly to error recovery in a motion video decompression system. The present invention utilizes motion vector estimation to recover video signals, with errors generated by the transmission state (nearly to the original video) thereby preventing damage due to the error.
2. Discussion of Related Art
With the rapid development of digital signal processing technology, greater amounts of motion video signals are compressed and transmitted through transmission channels of limited bandwidth. Thus, if an error occurs on the transmission channel during transmission of a motion video signal, the quality of recovered video would be lowered significantly. When an error occurs in the coded video data, the recovered video may be displayed in one of a variety ways, depending upon the coding system utilized.
Particularly, under the standards of the Motion Picture Experts Group (MPEG), motion video is divided into 16xc3x9716 blocks, where each block is called a macroblock. A plurality of macroblocks makes a slice, and depending upon the video size, a plurality of slices makes one frame.
The MPEG system utilizes a transform coding method and a motion compensation coding method. In such system, if an error occurs in even one bit of a bit row, the continuous macroblocks corresponding to the bit row on which the error is generated are damaged and thus, a large range of video information is lost. The effects of the damaged and lost video data continues to the next several frames. As a result, decoding the bit streams which were transmitted utilizing the coding procedure described above may result in a severely deteriorated quality of video data.
Accordingly, various recovering methods have been developed in the related art by which lost information is compensated using the normally recovered information adjacent to the lost data, thereby restoring the lost video data nearly to the original video. Although an error correcting code can be used, the normally recovered data adjacent to the lost data is used in order to maximize the limited bandwidth of the transmission channel. FIG. 1 shows a frame of 16xc3x9716 macroblocks to illustrate a conventional error concealment method of a motion video decompression system in the related art.
Generally, the conventional error concealment method used in the digital TV is classified into a temporal predicted error concealment method and a spatial predicted error concealment method, according to the video information. The temporal predicted error concealment method utilizes the redundant information between two consecutive frames while the spatial predicted error concealment method utilizes a spatial redundancy in the frame in which the information is included.
More specifically, the temporal predicted error concealment method is executed based upon the sequential videos which have time-correlation with each other. As shown in FIG. 1, the lost video data of a macroblock E1 within a current frame CF is replaced by a macroblock E1xe2x80x2 in the same position of a previous frame PF.
On the other hand, the spatial predicted error concealment method compensates the lost macroblock by using the macroblocks of the current frame which were not lost, rather than using the information of the previous frame. As shown in FIG. 1, the video data of a lost macroblock E1 is replaced with the data of any adjacent macroblock C1-C8 which were not lost.
However, the conventional error concealment methods as described above have several problems. First, in the conventional temporal predicted error concealment method, the motions of the lost macroblocks are not considered. When a large amount of the motion exists between two successive frames, even if the macroblock E1xe2x80x2 of the previous frame PF is at the same position as the lost macroblock E1, the coded information would greatly differ from the original macroblock, resulting in a deterioration of the video quality.
Also, in the conventional spatial predicted error concealment method, when spatial correlation is reduced between the lost macroblock and the adjacent macroblocks, the video of the restored block may be significantly different from the original video, resulting in the deterioration of the video quality.
Accordingly, an object of the present invention is to solve at least the problems and disadvantages of the related art.
An object of the invention is to provide an error concealment method of a motion video decompression system with an improved video quality.
Specifically, the object of the invention is to provide an error concealment method of a motion video decompression system capable of estimating motion of a lost macroblock within a frame according to the type of input video by using the motion vector of macroblocks adjacent to the lost macroblock to restore the video in the lost macroblock to nearly the original video.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objects and advantages of the invention may be realized and attained as particularly pointed out in the appended claims.
To achieve the objects and in accordance with the purposes of the invention, as embodied and broadly described herein, an error concealment method of a motion video decompression system includes estimating the motion information of a lost video; and restoring the lost video from the video adjacent to the lost video by using the estimated motion information.